574 



Transactions. — Physics. 

 Series 2. 



First Coil. 



Second Coil. 



Having thus ascertained the composition of the various 

 fractions, the freezing-point curve cau now be considered. At 

 the point X, where the first minimum occurs, the palmitic ana 

 stearic acids are in the proportion of 4 to 1. (See fig. 1.) 

 Now, when the pure compounds are mixed in these proportions 

 a eutectic mixture is formed. On adding a fixed quantity 

 of oleic acid to palmitic and stearic acids, it was found that 

 the composition of the eutectic mixture was not altered. 

 Consequently, as the percentage of oleic acid in the neigh- 

 bourhood of X varies only to a slight extent, the minimum 

 observed in the freezing-pjint curve must be due to the 

 formation of a eutectic mixture between the palmitic and 

 stearic acids. 



The following are the details of the experiments performed 

 to prove this conclusion : Definite mixtures of pure palmitic 

 and stearic acids were taken, and the freezing-points were 

 uetern lined. These results are represented in fig. 4. 25 per 

 cent, of oleic acid was then added, and another series of 

 freezing-point determinations was made. This formed a 

 second curve. By employing 40 per cent, of oleic acid a third 

 curve was obtained, and this was found to be approximately 

 parallel to the other two. Further than this, the eutectic 



